1. Field of the Invention
This invention relates to hydrogels; more particularly, but not exclusively, this invention relates to hydrogels which may be used as interfaces between damaged outer human and animal tissue, such as epidermal or epithelial tissue (hereinafter termed a wound) and its external environment.
This invention also relates to controlled release compositions comprising the hydrogels and an active substance, for example a medication system; to processes for preparing the controlled release compositions; and to methods of utilising the medications thereof, especially in vivo.
2. Description of the Prior Art
In the treatment of burns or other (post-operative, accidental or dermatological) tissue damage it is highly desirable to provide such an interface as aforesaid. Ideally, the interface should protect the wound from physical trauma; from agents of infection, such as airborne fungi, bacteria and viruses, gaining access to the wound; should prevent maceration of the scab and healing tissue by controlling the moisture of the wound. In addition, if desired, the medication should also maintain medication in contact with the wound.
Present gauze dressings such as leno weave dressings, are opaque after application and need frequent change to observe the healing process and to apply medication. This causes patient discomfort, particularly where wound exudate has dried and consolidated the dressing and the wound. Moreover, they do not exclude agents of infection, nor do they control the moisture of the wound: it is simply absorbed.
Hydrogels have already been indicated for use as a wound dressing but these have generally been natural and semi-synthetic products such as collagen, gelatin and starch products. These materials are not normally transparent; moreover, proteinaceous hydrogels can be allergenic; furthermore, they do not control the agents of infection, indeed, they may provide a nutrient source.